clear all 
close all
pkg load signal
[y,fs] = audioread('modulator22.wav');
sound(y, fs);
n = length(y); 
t=0:1/fs:(n-1)/fs; % time range
spectrogram(y,fs,5,30);

[y, fs] = audioread('modulator22.wav');
n = 30;
fc = 1000/(fs/2);
w = hamming(n+1);
b = fir1(n, fc, w);
filtered_signal = filter(b, 1, y);
spectrogram(filtered_signal,fs,5,30);
sound(filtered_signal, fs);
audiowrite('FIR.wav',filtered_signal,fs);